It is known that in general, for dielectric resonators for microwave circuits or temperature compensation ceramic (porcelain) capacitors or the like, dielectric ceramic (porcelain) compositions are required to have a high dielectric constant .epsilon. .sub.r and unloaded Q (Q.sub.u =1/tan.delta.), and it must be possible to design them with any desired value for the temperature coefficient .tau. .sub.f of the resonant frequency above or below zero, i.e., with a positive or negative temperature coefficient. Conventionally, such compositions included Bao.TiO.sub.2 systems, MgTiO.sub.3.CaO systems, ZrO.sub.2.SnO.sub.2.TiO.sub.2 systems, and BaO.TiO.sub.2.Sm.sub.2 O.sub.3.La.sub.2 O.sub.3 systems (see for example Japanese Patent Kokoku Publication No. 61-14606).
When dielectric resonators or capacitors were manufactured with these compositions, however, their dielectric constant .epsilon. .sub.r was 60 to 80 when their temperature coefficient .tau. .sub.f was in the region of 0 (ppm/.degree.C.), and this value of dielectric constant was too small to permit the resonator to be made compact.